TCA precipitation, what is the best solution to dissolve followed by Mass spectr - (Jul/03/2007 )

As the title. I have some proteins precipitated by TCA, then what is the solution to use to dissolve this protein chip. followed by mass spectrometry? water? tris? or urea?
I just wondered which solution gives less interference with LC-MS?or does not matter?
one guy told me that he use urea/reduction, then trypsin digestion, what is this urea do?
really confused.

Cathy

up again